Seeking assistance from Australia to find John Fitzgerald Youghal

Australian going slowly mad trying to find my 3rd great grandfather's (John Fitztgerald) details!! Our Fitzgerald family have taken pride in this name for generations here in Australia, particularly in Portland New South Wales. John Fitzgerald was the first of our Fitzgerald clan to come to Australia.

My Uncle did pre-internet research in the 90s, with little luck. I have looked at his marriage certificate from 1882 when he married my 3rd great grand mother Mary Ellen Fisher here in Echuca Victoria and his father's name is a very helpful (not lol) John Fitzgeraldand his mother is Catherine Giarch. However, my Uncle believed that it was actually Finch, but Im now (after some research) thinking it was actually Lynch.

Our John was the informant on most of his children's birth records and this is where I have located that he has Youghal recorded on 2 of them and just Cork on a couple of others. He has also recorded various years of birth for himself on the children's birth records. He has recorded 1848, 1845, 1846, and 1847. His marriage certficiate has his date of birth as 10 March 1847.

I havent been able to find when or where he came to Australia. Assuming he was the real father of his eldest daughter, the earliest I have him in Australia is 1875 (John was a rouge out here when it came to women!, 2 warrants issued for deserting 2 different women lol).

I have been able to locate a parish bapstism documents where a John Fitzgerald and a Catherine Lynch from Youghal had a John Fitzgerald baptised on 14 march 1847 with sponsors Eliza Lynch and Edmund ?? (Jaier??) with a residence that is a little illegible and not being from the area would have no idea what it might mean. I have uploaded the record.

Any assitance would be greatly appreciated!

Bernadette